Police in northwestern China detained about 20 ethnic Tibetan Buddhist monks on Thursday following anti-Chinese protests in February, according to a Beijing-based source with wide contacts among Tibetans.
Another 100 people who tried to prevent the police from detaining the monks, were also taken away by the police, the source said.
The monks in Tongren, in the remote Qinghai province, protested in February after police disrupted a Buddhist ceremony in the local monastery, shouting slogans calling for religious freedom and wishing exiled Tibetan spiritual leader the Dalai Lama a long life, the source said.
Pro-Tibet protesters have also dogged the global torch relay for the 2008 Olympic Games to be hosted by Beijing.
Police used tear gas to disperse the crowd in Tongren and detained some 200 monks. But the next day, thousands of monks marched in protest around the county seat, and the local government released the monks who had been arrested a day earlier, the source added.
Further protests were then held by the monks from the monastery, whose name in Chinese the source gave as Longwu.
The source did not know the precise reason for the latest detentions.
The protest in Tongren came before a series of pro-Tibet independence demonstrations in Lhasa from March 10 and unrest that spread to other Tibetan areas.
China has accused the Dalai Lama of orchestrating the violence in Tibet and other Tibetan areas of the country in a push for independence and to derail the Olympic Games which China hosts this summer.
But the Dalai Lama has rejected the accusations, speaking out against the use of violence, calling for talks with China and backing the Beijing Games.
Telephone calls to the Qinghai provincial government spokesman's office seeking comment were not answered.
Separately, the official Xinhua news agency said that two monks who had participated in riots in Gansu province had "surrendered to authorities".
Since the unrest, Chinese security forces have sealed off ethnic Tibetan parts of Western China and Tibet has been closed to tourists.
Chinese official media has reported that the region will reopen to foreign tourists from May 1, but on Thursday, a Foreign Ministry spokeswoman said that date was not confirmed.
"I think the government of the Tibetan Autonomous Region will make an assessment of the local situation and take a decision according to local conditions," she told a news conference.